1. Field of the Invention
The present invention relates to samplers, particularly to water samplers used to collect samples of water from the ocean and from lakes or rivers.
2. Summary of the Prior Art
The best-known sampler of this general type is a sampler known among those skilled in the art as the "Niskin Bottle", as described in U.S. Pat. Nos. 3,489,012 and 3,815,422. In fact, the instantly disclosed invention is an improvement over the Niskin Bottle and the full disclosure of the two patents is herewith incorporated by reference.
A number of other patents are pertinent in this respect, namely the following U.S. Pat. Nos.:
______________________________________ 3,242,740 3,425,664 3,986,635 4,037,477 4,091,676 4,106,751 4,302,974 4,347,751 4,593,570 4,744,256 4,852,413 5,094,113. ______________________________________
In briefly reviewing the Niskin Bottle, as quite aptly described also in U.S. Pat. No. 5,094,113, it includes a generally cylindrical tubular body with two lids on either sides which are biased closed by a resilient rubber band clamped between the two lids. The tubular body is formed of hard PVC material. After the sample is taken, the same is retained in the sampler for a certain period of time before it is analyzed. Any contamination of the sample, which would lead to false analysis results, must thereby be strictly avoided. Analytic instruments have become increasingly sophisticated, so that only slight alterations and contamination of the sample often have an adverse effect on the testing outcome. When the sample remains in the bottle for a time period in the order of one or a few hours, for instance, false results in terms of concentration in the water sample results. In some instances it is also necessary to avoid contact of the water sample with air when the water sample is extracted from the sampler.
In a more specific example, the sampler is immersed in sea water at a given depth, often as much as three miles, or even more. The sample is then encapsulated by closing the end caps. It takes a certain amount of time to bring the sampler back to the surface and prepare the same for analysis. During that time period, the rigid PVC body of the prior art sampler can contaminate the water sample by reacting with the water and the impurities contained therein. Furthermore, when the liquid is purged from the sampler, air is allowed to enter the device through the air vent, in order to equilibrate the pressure and to facilitate the purge. This causes the air to come in contact with the water sample and gases entrapped in the water sample to be released. All of this results in an incorrect reading of the actual amounts and concentration of elements in the water sample. Finally, the rigid PVC body is a relatively good conductor with regard to temperature exchange between the ambient atmosphere and the water sample contained therein. Accordingly, the sample will rather quickly assume the temperature of its environment while it is prepared for analysis.